Eating Meat Linked to Cataracts, Study Finds Vegetarian Diet Helps Eyes

Summary
Speculations and studies have indicated that some dietary factors can increase the predisposition to developing cataracts. However, no studies have specifically looked at the link between vegetarianism and cataracts. This study explored the association and found that the risk of cataract development was the highest in meat-eaters and progressively decreased in people who ate less meat, exclusive fish eaters (who did not eat other meat), vegetarians, and also vegans, respectively. The authors concluded that vegetarians were less likely to develop cataracts than carnivores.

Introduction
Cataracts cause misting and clouding of the normally transparent eye lens. If not treated, this condition can lead to a loss of vision. The only effective treatment is surgical replacement of the lens with an artificial lens. Cataracts mainly affect the elderly. They cause 48 percent of blindness worldwide, affecting some 18 million people. Cataract surgery is one of the commonest operations that people undergo voluntarily across the world. Some common factors that raise the risk of developing cataracts include diabetes, age, smoking, and exposure to the sun’s harmful ultraviolet B rays. Studies have shown that a healthy diet rich in vitamins C and E, and also carotenoids and minerals found in fruits and vegetables, can protect against development of cataracts. However, there have been no significant studies that investigated whether vegetarianism protects against cataracts. This study was undertaken to explore such benefits from vegetarianism.

Methodology

  • The study was completed by 57,446 people of both sexes and aged above 20 years.
  • Initially, all the participants answered questionnaires about their diet, smoking, amount of exercise, alcohol intake, weight, height, socioeconomic status and reproductive history. The questionnaire also measured food intake of 130 food items in the previous 12 months.
  • The subjects were divided into four categories, based on their dietary patterns. The first included meat-eaters, and the second group had fish-eaters who did not eat meat. The third group comprised vegetarians who ate vegetables, milk products, and eggs, and the fourth group were vegans who ate no meat, fish, eggs, and milk products.
  • All the subjects were followed till 2009 for development of cataracts. 27,670 participants’ diet and food intake were analyzed in relation to the incidence of cataracts.

Results

  • The incidence of cataracts among the subjects was 5.4 percent over the period of follow up.
  • Of the cataract cases, 32 percent had cataracts linked to elderly age group or senile cataracts. The remaining 68 percent had cataracts due to unspecified reasons.
  • Results also showed that cataract cases were more overweight, got less exercise, were smokers, were poorly educated, and made less money compared to those who did not get cataracts. These people were also more likely to have suffered from high blood pressure and high blood cholesterol.
  • After considering all the other risk factors mentioned, it was seen that the risk for cataracts was the greatest in meat eaters and progressively lesser in fish eaters’ group, vegetarians and finally, the least in vegans.

Next Steps/Shortcomings
The authors admit that the risk of cataracts was significantly lower in vegetarians but most of the vegetarians in this study were of Indian origin. They agree that ethnicity might have some role to play in decreased causality of cataracts among this group. They also admit that there might be other factors among vegetarians such as vitamin supplement intake etc., which affect their risk of cataracts, and these need to be studied further.

Conclusion
This study shows that vegetarians and vegans have a lower risk of developing cataracts compared to those who eat meat and fish. Although the researchers have found some other factors like smoking, lack of exercise, and excess weight, high blood pressure and high blood cholesterol to contribute to cataract risk, they agree that diet plays a significant role. In their assessment, they adjusted for all these individual risks before concluding that cataract risk decreases with vegetarianism. The authors suggest more research to confirm these results and agree that there is evidence that some vitamins and minerals present in diet do contribute to a lower risk of cataract in some individuals.

For More Information:
Diet, Vegetarianism, and Cataract Risk
American Journal of Clinical Nutrition, March 2011
By Paul N Appleby; Naomi E Allen
From the University of Oxford, Oxford, United Kingdom

*FYI Living Lab Reports Are Summaries of the Original Research.

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